High-strength sealed connection for expandable tubulars

ABSTRACT

A radially expandable sealed tubular joint for use in oil and gas wells having a pair of radially expandable tubular elements each having threading at a free end thereof and coupled to one another to form a flush joint connection, the threading including hooked incomplete threads located at least adjacent the free ends, and a sealing substance extending between and adhering to the threading of one element and the threading of the other element, wherein after a radial expansion of the coupled pair of elements the sealing substance remains extended between and adhered to the threading of one element and the threading of the other element. The sealing substance is either a greaseless elastomeric sealant coated on one or both of the pair of elements or a pure metal applied to each of the pair of elements.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a high-strength connection forexpandable members, and more particularly, to a threaded flush jointconnection for radially expandable tubulars, such as tubulars used inthe oil and gas industry.

2. Description of Related Art

In a typical oil or natural gas well drilling environment, a pluralityof tubulars, e.g., pipes, are inserted one at a time into a well borehole in strings of different diameters, thus forming a telescopic welldesign. The assembly of such pipes used in the oil and gas industry iscommonly performed using threaded joints or connections, the standardsfor which are described and specified by the American PetroleumInstitute (“API”). These connections have limitations when subjected toextreme loading conditions, which are increasingly common in today's oiland gas wells. This is especially true with connections used in a highinternal or external gas pressure environment, where the risk of leaksmust be eliminated, yet the connections must resist high mechanicalloading conditions caused by tension or other loads.

One of the newest and most demanding technologies used in oil and gaswell drilling today is “expandable technology.” In accordance with thistechnology, a tubular member, e.g., a pipe, may be radially expanded bymeans of a mandrel after the pipe has been lowered into a well, whichmandrel is moved along the internal diameter of a string of such pipes.Each pipe in the string is enlarged in place to allow other pipes to belowered and expanded as well, so that ultimately all the pipes in thewell have the same internal diameter, thereby avoiding the reduction ininternal diameter of the ordinary telescopic well design. Today, such astring of pipes is normally radially expanded by more than five percent,with the industry targeting expansions of greater than twenty percent,based on an internal diameter of the pipe being expanded. One process ofexpanding tubulars is described in detail in U.S. Pat. No. 5,348,095 toWorrall et al., which is incorporated herein by reference. Analternative expansion method, which utilizes rotary devices, isdescribed in detail in U.S. Pat. No. 6,457,532 to Simpson, which is alsoincorporated herein by reference. Yet another alternative method ofexpanding expandable tubulars is described in substantial detail in U.S.Pat. No. 6,604,763 to Cook et al., which is also incorporated herein byreference.

At first, the expandable tubulars or tubular members, e.g., pipes, andthe connections to join them were mainly used for casing remediation orsimilar applications, where the length of the string of pipes wasrelatively small, thus allowing for low-strength connections. However,with increasing well depths and the consequent increase in the length ofthe string of pipes, an important design element to be considered is theincreased strength of the connection needed. Previous expandableconnections, such as the connections in expandable tubular technologyutilizing slotted pipes as tubulars, needed only to withstand loadsassociated with the running and expansion processes. However, astechnology for the expansion of solid (i.e., neither slotted norperforated) tubulars is being spread within the oil and gas industry,another tubular connection design element that should be consideredrelates to the capability of the connections to assure fluid and/or gastightness against internal pressure, external pressure, or both.

To provide a high-strength connection between two tubulars, differentalternatives have appeared in the oil and gas industry, such as theso-called “upset ends” and “coupling” connections. However, the leastproblematic radial expansion processes require that the connection andthe tubular members have substantially the same wall thicknesses so thatthe force necessary to deform (i.e., radially expand) the string ofpipes is substantially constant as a mandrel, for example, is movedalong the pipe string. As such, the connections should preferably be ofthe type known in at least the oil and gas industry as “flush joint” or“integral flush joint”, in which the connections are threaded within thewall thickness of the tubular member, with a male threaded element atone end of the tubular member and a female threaded element on the otherend. The external diameter of such a flush joint connection is the samefor both tubular members that are to be “made up,” or threaded togetherand torqued, to achieve a desired connection and seal. In these flushjoint connections, however, any device (e.g., an O-ring) that is placedwithin the threads or at the ends of the threaded areas of coupledtubular members diminishes the “critical area”, also known as theresistant area. For the female tubular member, this critical area of theconnection is the area defined as the circular ring bounded by theexternal diameter of the connection and the diameter of the thread rootof the female member at the last engaged thread of the male member; andfor the male tubular member, this critical area is the circular ringbounded by the diameter of the thread root of the male member at thelast engaged thread of the female member and the internal diameter ofthe connection. Therefore, devices placed within the wall thickness,such as O-rings (see, e.g., U.S. Pat. No. 6,409,175 to Evans et al.),will reduce this critical area and consequently the tensile resistanceof the threaded connection, which in turn limits the length of thetubular string and the depth that can be achieved therewith as thereduced critical area cannot withstand the required higher loading. Assuch, a need exists in at least the oil and gas industry for anexpandable connection, such as a threaded flush joint connection, havingan improved critical area that can withstand today's high loads.

To assure a threaded connection's sealing response, some standardconnections in the oil and gas industry rely on metal-to-metal sealsplaced at various points in the joints depending on the joint design,which points are selected to improve the leak resistance of theconnection. This type of seal in a threaded joint provides a barrier togas or liquid pressure while the threads provide mechanical support andhelp or even improve stabbing and running characteristics. One exampleof this type of metal-to-metal seal is the API “Extreme-Line” joint, asdefined by API Standard 5B. Several seal design alternatives tometal-to-metal seals have been proposed in the known art. For example,other connections make use of a resilient seal located at a givenposition along the threaded area, wherein this resilient sealplastically deforms during make up of the connection and the connectionobtains sealability as a consequence of the thread gaps being closed bythe compression of the resilient material between the mating elements(i.e., within the thread gaps). In another type of connection, smallgaps formed between the threads of the mating members of the connectionare filled with an API Modified Thread Compound, which is a threadcompound that is formulated in accordance with the requirements ofobsolete API Bulletin 5A2 (i.e., a grease-based compound). All of thesetypes of sealing mechanisms cannot work properly in an expandablethreaded tubular connection after a radial expansion thereof, as thereis a tendency for the threads of the female tubular member to shift orseparate from the threads of the male tubular member thereby creatingleak paths along the connection.

In expandable threaded connections, yet another design aspect thatshould be considered is the design of the threads. Conventional threaddesigns for expandable threaded connections have included (i) “perfectthreads”, as shown for example in FIG. 15A, which are threads havingnormal (i.e., perfect) roots and normal (i.e., perfect) crests, such asdisclosed in U.S. Patent Application Publication No. 2003/0107217A1 toDaigle et al., and (ii) “hooked threads”, as shown for example in FIG.15B, such as disclosed in U.S. Pat. No. 6,409,175 to Evans et al.However, a need remains in the oil and gas industry for an expandablethreaded connection having strength greater than that obtained withthese conventional forms of threading.

Finally, some connections have been developed for use with expandabletubulars, which are disclosed in varying detail in the following patentsand patent applications: U.S. Pat. No. 6,409,175 to Evans et al.;European Publication No. 1106778A1; and U.S. Patent ApplicationPublications No. 2002/0163192A1 to Coulon et al., No. 2003/0067166A1 toSivley, IV, and No. 2003/0107217A1 to Daigle et al.

However, despite the conventional connections described above forradially expandable tubular members, a need remains in the oil and gaswell drilling industry for a high strength, yet simple to manufactureand easily made up, expandable threaded connection that remains sealedafter a radial expansion thereof and which can sustain the increasingloads being placed on such connections as a result of today'sincreasingly deeper, higher pressure wells.

SUMMARY OF TH INVENTION

This invention addresses the foregoing needs in the art by providing, ina preferred embodiment of the present invention, a radially expandablethreaded tubular assembly comprising (i) a radially expandable malethreaded element having external male threading and a first free end,the external male threading including a first incomplete thread and afirst hooked thread, the first incomplete thread being located at leastadjacent the first free end of the male threaded element; (ii) aradially expandable female threaded element having internal femalethreading and a second free end, the internal female threading includinga second incomplete thread and a second hooked thread, the secondincomplete thread being located at least adjacent the second free end ofthe female threaded element, the female threaded element beingthreadedly engaged with the male threaded element; and (iii) anelastomeric sealant extending between the external male threading andthe internal female threading and adhering to both the external malethreading and the internal female threading. The elastomeric sealant iscapable of being elongated after curing while remaining extended betweenand adhered to the external male threading and the internal femalethreading.

In another aspect of a preferred embodiment of the present invention,the elastomeric sealant is capable of being elongated at least about 45percent after curing while remaining extended between and adhered toeach of the external male threading and the internal female threadingand has an elastic modulus less than about 2.0 MPa (290 p.s.i.). Morepreferably, the elastomeric sealant is capable of being elongated atleast about 100 percent after curing while remaining extended betweenand adhered to each of the external male threading and the internalfemale threading and has an elastic modulus less than about 1.0 MPa (145p.s.i.). Even more preferably, the elastomeric sealant is capable ofbeing elongated at least about 400 percent after curing while remainingextended between and adhered to each of the external male threading andthe internal female threading and has an elastic modulus between about0.5 MPa (73 p.s.i.) and about 2.0 MPa (290 p.s.i.).

In yet another aspect of a preferred embodiment of the presentinvention, the elastomeric sealant is adhered to each of the externalmale threading and the internal female threading with anadhesion-to-rigid-substrate of at least 0.35 MPa (51 p.s.i.), and morepreferably with an adhesion-to-rigid-substrate of at least 0.7 MPa (102p.s.i.). Additionally, the elastomeric sealant is preferably agreaseless elastomeric sealant, which is preferably capable of curing inthe absence of oxygen and in the absence of humidity.

In yet another aspect of a preferred embodiment of the presentinvention, the greaseless elastomeric sealant is a polysulfide sealantor a polyurethane sealant, which is preferably a viscous paste or aliquid before curing and is a rubber-like solid after curing. Moreover,the male threaded element and the female threaded element mostpreferably threadedly engage each other to form a flush jointconnection.

In yet another aspect of a preferred embodiment of the presentinvention, each of the first incomplete thread and the second incompletethread has a perfect crest and an imperfect root. Also, each of thefirst incomplete thread and the second incomplete thread is mostpreferably a hooked thread, the first incomplete thread is preferablythe initial thread adjacent the first free end of the male threadedelement, and the second incomplete thread is preferably the initialthread adjacent the second free end of the female threaded element.Furthermore, in yet another aspect of a preferred embodiment of thepresent invention, at least one of the male threaded element and thefemale threaded element includes a torque shoulder, and most preferablya reverse torque shoulder.

In another preferred embodiment of the present invention, a radiallyexpandable threaded tubular assembly comprises (i) a radially expandablemale threaded element having external male threading and a first freeend, the external male threading including a first incomplete thread anda first hooked thread, the first incomplete thread being located atleast adjacent the first free end of the male threaded element; (ii) aradially expandable female threaded element having internal femalethreading and a second free end, the internal female threading includinga second incomplete thread and a second hooked thread, the secondincomplete thread being located at least adjacent the second free end ofthe female threaded element; (iii) a first metallic coating disposed onand adhered to the external male threading; and (iv) a second metalliccoating disposed on and adhered to the internal female threading. Thefemale threaded element is threadedly engaged with the male threadedelement and the first metallic coating is cold welded to the secondmetallic coating.

In another aspect of a preferred embodiment of the present invention,each of the first metallic coating and the second metallic coating is aductile metal and has a yielding tension less than about 100 MPa (14.5k.s.i.), more preferably a yielding tension less than about 50 MPa (7.25k.s.i.), and most preferably a yielding tension less than about 20 MPa(2.9 k.s.i.). In addition, each of the first metallic coating and thesecond metallic coating preferably allows a principal shear strain of atleast about 100 percent without fracturing and without fissurepropagation.

In yet another aspect of a preferred embodiment of the presentinvention, one of the first metallic coating and the second metalliccoating is an alloy, and the other of the first metallic coating and thesecond metallic coating is an alloy or a pure metal. Preferably, each ofthe first metallic coating and the second metallic coating is a puremetal, and even more preferably, the pure metal contains 99.99 percentby weight of a single metal. Moreover, in yet another aspect of apreferred embodiment of the present invention, the single metal isselected from the group consisting of Copper, Aluminum, Lead, Zinc, Tinand Magnesium, and most preferably is selected from the group consistingof Lead, Zinc and Tin.

In yet another aspect of a preferred embodiment of the presentinvention, each of the first metallic coating and the second metalliccoating has a thickness at least about one-sixteenth of a gap betweenthe engaged internal female threading and the external male threading.In addition, each of the first metallic coating and the second metalliccoating preferably has substantially the same thickness and is of thesame pure metal.

In yet another preferred embodiment of the present invention, a methodof forming a sealed tubular joint includes the steps of (i) providing afirst radially expandable tubular member having external male threadingand a first free end, the external male threading including a firstincomplete thread and a first hooked thread, the first incomplete threadbeing located at least adjacent the first free end of the first tubularmember; (ii) providing a second radially expandable tubular memberhaving internal female threading and a second free end, the internalfemale threading including a second incomplete thread and a secondhooked thread, the second incomplete thread being located at leastadjacent the second free end of the second tubular member; (iii) coatingat least one of the external male threading and the internal femalethreading with an elastomeric sealant; (iv) coupling the first tubularmember and the second tubular member, the coupling thereby providing athreaded connection; (v) disposing the elastomeric sealant between theexternal male threading and the internal female threading and intoadherence with each of the external male threading and the internalfemale threading; (vi) curing the elastomeric sealant, the curingthereby providing a cured elastomeric sealant extended between andadhered to the external male threading and the internal femalethreading; and (vii) radially expanding the threaded connection. In thispreferred embodiment, the cured elastomeric sealant is capable of beingelongated while remaining extended between and adhered to the externalmale threading and the internal female threading.

In another aspect of a preferred embodiment of the present invention,the threaded connection is radially expanded at least about five percentbased on an inside diameter of the threaded connection. More preferably,the threaded connection is radially expanded at least about fifteenpercent based on an inside diameter of the threaded connection.

In another aspect of a preferred embodiment of the present invention,the elastomeric sealant is a greaseless elastomeric sealant, each of theexternal male threading and the internal female threading is coated withthe greaseless elastomeric sealant in the coating step, and the curedelastomeric sealant (i) is capable of being elongated at least about 400percent while remaining extended between and adhered to the externalmale threading and the internal female threading, (ii) is adhered toeach of the external male threading and the internal female threadingwith an adhesion-to-rigid-substrate of at least 0.7 MPa (102 p.s.i.);and (iii) has an elastic modulus between about 0.5 MPa (73 p.s.i.) andabout 2.0 MPa (290 p.s.i.).

In yet another preferred embodiment of the present invention, a methodof forming a sealed tubular joint includes the steps of (i) providing afirst radially expandable tubular member having external male threadingand a first free end, the external male threading including a firstincomplete thread and a first hooked thread, the first incomplete threadbeing located at least adjacent the first free end of the first tubularmember; (ii) providing a second radially expandable tubular memberhaving internal female threading and a second free end, the internalfemale threading including a second incomplete thread and a secondhooked thread, the second incomplete thread being located at leastadjacent the second free end of the second tubular member; (iii) coatingthe external male threading with a first metallic coating, the firstmetallic coating being a first pure metal and adhering to the externalmale threading; (iv) coating the internal female threading with a secondmetallic coating, the second metallic coating being a second pure metaland adhering to the internal female threading; (v) coupling the firsttubular member and the second tubular member, the coupling therebyproviding a threaded connection, the coupling cold welding the firstmetallic coating together with the second metallic coating; and (vi)radially expanding the threaded connection. After the radial expansionof the threaded connection (i) the first metallic coating remainsadhered to the external male threading, (ii) the second metallic coatingremains adhered to the internal female threading, and (iii) the firstmetallic coating and the second metallic coating remain cold weldedtogether.

In yet another preferred embodiment of the present invention, anexpandable sealed tubular joint comprises a pair of radially expandableelements each having threading at a free end thereof and coupled to oneanother, the threading including hooked incomplete threads being locatedat least adjacent the free ends; and a sealing substance extendingbetween and adhering to the threading of one radially expandable elementand the threading of the other radially expandable element, whereinafter a radial expansion of the coupled pair of radially expandableelements the sealing substance remains extended between and adhered tothe threading of one radially expandable element and the threading ofthe other radially expandable element.

In another aspect of a preferred embodiment of the present invention,the sealing substance is a greaseless elastomeric sealant that (i) iscapable of being elongated at least about 100 percent while remainingextended between and adhered to the threading of one radially expandableelement and the threading of the other radially expandable element, (ii)is adhered to the threading with an adhesion-to-rigid-substrate of atleast 0.35 MPa (51 p.s.i.); and (iii) has an elastic modulus betweenabout 0.5 MPa (73 p.s.i.) and about 2.0 MPa (290 p.s.i.).

In yet another aspect of a preferred embodiment of the presentinvention, the sealing substance is a pure metal containing 99.99percent by weight of a single metal selected from the group consistingof Copper, Aluminum, Lead, Zinc, Tin and Magnesium, the coupled pair ofradially expandable elements form a flush joint connection, and thehooked incomplete threads have perfect crests and imperfect roots.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a partial sectional view of a radially expandable, threaded,tubular, flush joint connection representing one embodiment of thepresent invention.

FIG. 2 is a partial cross-sectional view of a threaded connection of apreferred embodiment showing a coupled pin and box.

FIG. 3 is an enlarged detailed view showing hooked incomplete threads ofa box where the incomplete threads have normal crests and imperfectroots.

FIG. 4 is a detailed view of a thread design, which view juxtaposes ahooked thread design with a non-hooked thread design for purposes ofillustration.

FIG. 5 is a detailed view showing external male threading of a malethreaded element coated with a sealing substance.

FIG. 6 is a detailed view showing internal female threading of a femalethreaded element coated with a sealing substance.

FIG. 7 is a detailed view showing a process by which a sealing substanceis distributed or disposed between the threads of male and femalethreaded elements during make up and during a radial expansion process.

FIG. 8 is a partial cross-sectional view showing a threaded connectionbetween a pin and a box where the pin includes an external torqueshoulder.

FIG. 9 is a detailed view of a portion of FIG. 8, and shows across-sectional view of an internal torque shoulder.

FIG. 10 schematically shows a radial expansion process taking place on aplain end pipe.

FIG. 11 schematically shows a spring back movement at a free end of aplain end pipe as a mandrel is removed from within the plain end pipe.

FIG. 12 is a partial cross-sectional view showing an initial stage ofdeformation produced in a radially expandable threaded connection as amandrel is pushed through the inside of that threaded connection, andshowing threads of the pin and box being deformed.

FIG. 13 is a partial cross-sectional view showing a stage of radialexpansion of a threaded connection after a mandrel has passed by thethreads of a pin and a box.

FIG. 14 is an enlarged detailed view showing a pin nose of a pin engagedwith a reverse torque shoulder of a box, wherein that pin nose has notdeformed towards the inside of the threaded connection between the pinand the box as a consequence of a spring-back movement.

FIGS. 15A and 15B each show prior art threads, where FIG. 15A showsnon-hooked perfect threads, and FIG. 15B shows hooked perfect threads.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 generally shows a radially expandable threaded tubular assembly,which is an embodiment of the present invention. The tubular assembly 1generally comprises a radially expandable male threaded element 2 havingexternal male threading 3 and a first free end 4, a radially expandablefemale threaded element 5 having internal female threading 6 and asecond free end 7 (hereinafter, the external male threading 3 and theinternal female threading 6 are also collectively referred to as the“threading” of the threaded elements 2 and 5), and a sealing substance8, 8′ (see, e.g., FIGS. 5 and 6) extending between and adhering to thethreading (e.g., 3) of one radially expandable element (e.g., 2) and thethreading (e.g., 6) of the other radially expandable element (e.g., 5).The male and female threaded elements 2, 5 may be, for example, radiallyexpandable tubing, casing, or other solid expandable tubular, commonlyknown collectively within at least the oil and gas well drilling fieldas oilfield tubular goods and which are included within the scope of theterms “tubular(s)”, “tubular member(s)”, and “element(s)” as usedhereinafter. Similarly, in at least the oil and gas well drilling field,the male threaded element 2 is commonly referred to as a “pin” or “pinmember” and the female threaded element 5 is commonly referred to as a“box” or “box member”. As such, the terms “pin 2” and “box 5” are usedinterchangeably hereinafter to refer to the male threaded element 2 andthe female threaded element 5 respectively.

The pin 2 and box 5 are coupled together by threading the pin 2 into thebox and applying a desired, and usually predetermined, amount of torque.This coupling or engaging together of the pin 2 and the box 5 results ina tubular assembly 1, hereinafter referred to as a “joint”,“connection”, or “threaded connection”. The pin 2 and the box 5 areproperly threadedly engaged or “made up” when, for example, such apredetermined amount of torque is applied to the connection and a pinnose 9 (see, e.g., FIG. 14) of the pin 2 is in contact with an internaltorque shoulder 30 (described below) of the box 5. The threadedconnection of the pin 2 and the box 5 preferably form a flush jointconnection, as shown in FIG. 1. In the oil and gas well drilling field,such a flush joint or flush joint connection is, for example, aconnection with male and female threads cut directly into lengths ofpipe so as to provide the same, or substantially the same, innerdiameter and outer diameter throughout the connection as in the middleof the length of pipe once those lengths are joined, coupled, orconnected together. In conventional oil and gas wells, the box 5 isinstalled facing out of the well, and the pin 2 is installed facing downinto the well, as shown in FIG. 1. However, the present invention isalso applicable to other connection configurations, such as the pin 2facing out of a well with the box 5 facing down into the well, and alsoto a flush joint connection where the male threaded element 2 of each oftwo pipes are coupled together by a connector (e.g., a relatively shortsection of pipe) having two female threaded elements 5, and vice versa(not shown).

The details of the threading of the tubular assembly 1 will now bedescribed with reference to at least FIGS. 2 through 6. In a preferredembodiment, both of the external male threading 3 and the internalfemale threading 6 preferably include hooked threads and incompletethreads. In thread design, the term “incomplete threads” is usedinterchangeably with “imperfect threads”. More preferably, the threadsof the pin 2 and the box 5 include hooked incomplete threads (i.e., thethreads include incomplete threads that are also hooked). Additionaldetails of these hooked, incomplete, and hooked incomplete threads arediscussed below with respect to preferred embodiments of the presentinvention.

As shown in FIGS. 2, 3, and 14, each of the pin 2 and the box 5 includesthreads having incomplete or imperfect thread(s) 11, 12. Of note, theterms “thread”, “threads”, and “threading” are used interchangeablyherein, as it is to be understood, for example, that a “thread” or“threading” may include a plurality of “threads”, and likewise “threads”may comprise “threading” or a “thread”. The incomplete threads 11 of thepin 2 and the incomplete threads 12 of the box 5 each include “normal”or “perfect” crests 13 and imperfect roots 14. The normal or perfectcrests 13 of the incomplete threads 11 maintain the same, orsubstantially the same, taper as the rest of the crests of the threadsof the external male threading 3; and the perfect crests 13 of theimperfect threads 12 maintain the same, or substantially the same, taperas the rest of the crests of the threads of the internal femalethreading 6. However, unlike the perfect crests 13, the roots 14 of theincomplete threads 11, 12 do not have the same taper as the roots of therest of the threads of the pin 2 and the box 5, respectively, which iswhy these roots are deemed “imperfect” roots. Incomplete threads havingnormal crests and imperfect roots are used, for example, in API “extremeline” piping, and such incomplete threads are defined, for example, byAmerican Petroleum Institute (API) Standard 5B.

Furthermore, the incomplete threads 11 of the pin 2 are located at leastclose to or adjacent the free end 4 of the pin 2, and the incompletethreads 12 of the box 5 are located at least close to or adjacent thefree end 7 of the box 5, as shown, for example, in FIG. 2. Preferably,the initial thread (i.e., the first or the starting thread) of each ofthe pin 2 and the box 5 is an incomplete thread. More preferably, theincomplete threads 11, 12 constitute at least one tenth ({fraction(1/10)}th) the length of the total length of the threads of the pin 2and the box 5, respectively, starting from the free ends 4, 7.

Additional details of the preferred incomplete threads 11, 12 of thepresent invention are provided below with reference to FIG. 3. FIG. 3shows a detailed view of the free end 7 of the box 5 threadedly engagedor made up with the pin 2. As shown, the box 5 includes incompletethreads 12 formed by imperfect roots 14 and perfect crests 13. Inthreading design, “perfect” roots are fully formed roots (i.e., rootscut to a full depth consistent with the depth of roots of adjacentthreads), while “imperfect” roots are roots that are cut to less thanfull depth. With incomplete threads formed at the free end 7 of the box5, a preferred resistant area or preferred critical area 15 is definedin the pin 2 adjacent the last engaged thread 16 of the box 5, whichpreferred critical area 15 equals the Diameter of Imperfect Threads(labeled as DIT in FIG. 3), which in this case is the diameter of thethread root 19 adjacent the last engaged thread crest of the box 5,minus the Inside Diameter (labeled as ID) of pin 2. In other words, thispreferred critical area 15 is defined by the minimum wall thickness ofthe pin 2 at the location directly opposing the last engaged thread 16of the box 5. However, if there were no imperfect threads formed at thefree end 7 of the box 5, then a normal critical area 17 would be definedin the pin 2 adjacent the last engaged “full” or “perfect” thread 18 ofthe box 5, which normal critical area 17 equals the Diameter of PerfectThreads (labeled as DPT) minus the Inside Diameter (ID) of pin 2. Assuch, the preferred critical area 15 is larger than the normal criticalarea 17, thus enabling the joint to withstand higher loads (e.g., higheraxial loading). As explained above, the preferred and normal criticalareas 15, 17 of the pin 2 derive from the imperfect threads 12 of thebox 5. Likewise, the preferred and normal critical areas of the box 5derive from the imperfect threads 11 of the pin 2.

Also as shown in FIGS. 2, 3, 4, and 14, each of the pin 2 and the box 5preferably includes threads having a “hooked” thread design. This hookedthread design is explained below with reference to FIG. 4, which is apartial detailed view of a sample thread 20 on, for example, a pin,similar to the thread profile shown in FIG. 5. In FIG. 4, a hookedthread profile is juxtaposed with a non-hooked thread profile toillustrate the differences between the two thread forms. Load flankposition arrows 21, 21′ indicate the possible positions of a load flank23, 23′ of the sample thread 20. If an axis 24 of the load flank 23forms an angle α (alpha) with a line 25 that is perpendicular to thetubular member (e.g., pipe) longitudinal axis (not shown), then thethread profile is a “hooked thread” or “hooked thread profile.” Incontrast, if the axis 24′ of the load flank 23′ forms an angle β (beta)with the line 25, then the thread profile is a “non-hooked threadprofile.” The sample thread 20, whether on a pin or a box, also has astabbing flank 22. The stabbing flank 22 of each of the box and the pinface each other, so if one of them (e.g., the stabbing flank of the pin)points into a well, then the other one (e.g., the stabbing flank of thebox) faces to the opposite direction (i.e., out of the well).

In a preferred embodiment of the present invention, each of the externalmale threading 3 and the internal female threading 6 includes hookedthreads. Most preferably, all of the threading of the pin 2 and box 5 ishooked threading, including the incomplete threads. In other words, thethreading of the pin 2 and the box 5, including the incomplete threads,is most preferably hooked, as shown, for example, in FIG. 5, where loadflank 26 is shown having an angle α (alpha) greater than zero, inaccordance with the “hooked thread” discussion above with reference toFIG. 4.

In another aspect of the preferred embodiment, at least one of the pin 2and the box 5 includes a torque shoulder. As shown in FIG. 8, the pin 2preferably includes an external torque shoulder 29, which is formed at alocation so as to receive the free end 7 of the box 5. As shown in FIG.9, the box 5 preferably includes an internal torque shoulder 30, whichis formed at a location so as to receive the free end 4 of the pin 2.The internal torque shoulder 30 preferably is a reverse torque shoulder(30), that is, the internal torque shoulder 30 preferably has a negativeangle, which by hooking the pin nose 9 further prevents the pin nose 9from deforming toward the inside of the threaded connection. In FIG. 9,the angle of the face of the reverse torque shoulder 30 is shown asnegative torque shoulder angle γ (gamma). Angle γ (gamma) is measuredbetween a line 32 that is perpendicular to the tubular member (e.g.,pipe) longitudinal axis (not shown) and the face of the reverse torqueshoulder 30. An arrow 31 indicates the direction towards which the faceof the reverse torque shoulder 30 is able to move to be considered a“negative” or “reverse torque shoulder.” In addition, the pin nose 9 ofthe pin 2, which contacts the reverse torque shoulder 30, preferably hasa correspondingly angled face that is substantially parallel to the faceof the reverse torque shoulder 30. As such, the pin nose 9 and thereverse torque shoulder 30 engage each other (e.g., mate like pieces ofa puzzle) to prevent the first free end 4 of the pin 2 from curling ormoving inward towards the center of the tubular assembly after thetubular assembly has been expanded.

The sealing substance 8, 8′ extending between and adhering to thethreading (e.g., 3) of one radially expandable element (e.g., 2) and thethreading (e.g., 6) of the other radially expandable element (e.g., 5)is described below. The sealing substance 8, 8′ may be either (i) anelastomeric sealant or (ii) a metallic coating, each of which isindividually discussed in greater detail below.

Elastomeric Sealant. As shown in FIGS. 5 and 6, where the sealingsubstance 8, 8′ is an elastomeric sealant, at least a portion of thethreads of the pin 2 or at least a portion of the threads of the box 5is coated with that elastomeric sealant. Preferably, substantially allof the threads of both of the pin 2 and the box 5 are coated with theelastomeric sealant (see 8, 8′); however, the threads may also be coatedin a differential way along the threading to provide localized sealingpoints. The elastomeric sealant (see 8, 8′) is applied to the threads ofthe pin 2 and the box 5 before coupling thereof. The elastomeric sealant(see 8, 8′) is applied in an amount and thickness such that when the pin2 and the box 5 are coupled, thus forming a threaded connection, theelastomeric sealant (see 8, 8′) extends between the external malethreading 3 and the internal female threading 6 and adheres to both theexternal male threading 3 and the internal female threading 6. Theelastomeric sealant (see 8, 8′) is preferably a curable sealant, and iscapable of being elongated after curing while remaining extended betweenand adhered to the external male threading 3 and the internal femalethreading 6.

In a preferred embodiment of the present invention, the elastomericsealant (see 8, 8′) is capable of being elongated at least about 45percent after curing while remaining extended between and adhered toeach of the external male threading 3 and the internal female threading6 and has an elastic modulus less than about 2.0 MPa (290 p.s.i.). Morepreferably, the elastomeric sealant (see 8, 8′) is capable of beingelongated at least about 100 percent after curing while remainingextended between and adhered to each of the external male threading 3and the internal female threading 6 and has an elastic modulus less thanabout 1.0 MPa (145 p.s.i.). Most preferably, the elastomeric sealant(see 8, 8′) is capable of being elongated at least about 400 percentafter curing while remaining extended between and adhered to each of theexternal male threading 3 and the internal female threading 6 and haselastic modulus between about 0.5 MPa (73 p.s.i.) and about 2.0 MPa (290p.s.i.).

The elastomeric sealant (see 8, 8′) is also preferably a “greaseless”elastomeric sealant. In other words, the preferred elastomeric sealant(see 8, 8′) of the present invention has no grease base or component;thus, the main performance objectives of the preferred elastomericsealant (see 8, 8′) are bonding (ability to adhere), elongation, andsealing, and not lubrication. To illustrate, the reference standard forAPI Modified Thread Compound, which is a thread compound that isformulated in accordance with the requirements of obsolete API Bulletin5A2, requires a grease base of about 36 percent by weight. Further, APIRecommended Practice (RP) 5A3 sets forth that a primary purpose of theAPI Modified Thread Compound is to act as a lubricating material betweenmating connectors of a threaded connection. Because API Modified ThreadCompound contains such a grease base, the API Modified Thread Compounddoes not qualify as an elastomeric sealant (see 8, 8′) of the presentinvention.

Furthermore, in another aspect of a preferred embodiment of the presentinvention, the elastomeric sealant (see 8, 8′) adheres to each of theexternal male threading 3 and the internal female threading 6 with anadhesion-to-rigid-substrate of at least 0.35 MPa (51 p.s.i.). Thisadhesion-to-rigid-substrate is measured in accordance with ASTM D429-02a(Method A), which is known as the “Standard Test Methods for RubberProperty—Adhesion to Rigid Substrates.” More preferably, the elastomericsealant (see 8, 8′) adheres to each of the external male threading 3 andthe internal female threading 6 with an adhesion-to-rigid-substrate ofat least 0.5 MPa (73 p.s.i.). Most preferably, the elastomeric sealant(see 8, 8′) adheres to each of the external male threading 3 and theinternal female threading 6 with an adhesion-to-rigid-substrate of atleast 0.7 MPa (102 p.s.i.). Moreover, the preferred elastomeric sealant(see 8, 8′) is capable of curing in the absence of oxygen and in theabsence of humidity, and preferably in the absence of both oxygen andhumidity. The preferred elastomeric sealant (see 8, 8′) is also aviscous paste or a liquid before curing and is a rubber-like solid afterfully curing. The preferred elastomeric sealant (see 8, 8′) preferablyfully cures within two days, and more preferably fully cures in aboutone day or less.

In a most preferred embodiment, the elastomeric sealant (see 8, 8′) ofthe present invention is a greaseless polysulfide sealant or agreaseless polyurethane sealant. Examples of such most preferredelastomeric sealants (see 8, 8′), by way of non-limiting example,include the following commercially available sealants: (i) THIOKOL(Registered Trademark) 2282 High Performance Polysulfide Joint Sealant,available from PolySpec L. P., located at 6614 Gant Road, Houston, Tex.,which sealant has a published elongation property of about 450 to 500percent, fully cures in about one day, and has no grease base orcomponent; (ii) PSI-270/RC 270 Multi-Component Polyurethane ReservoirSealant, available from Polymeric Systems, Inc., located at 723Wheatland Street, Pheonixville, Pa., which sealant has a publishedelongation property of 450 to 550 percent as measured in accordance withASTM D 412, fully cures at 75° F. (24° C.) in about 2 days, has apublished adhesion-in-peel of 20 to 25 lb/in (3.5 kN/m to 4.4 kN/m) inaccordance with ASTM C 794, which is known as the “Standard Test Methodfor Adhesion-in-Peel of Elastomeric Joint Sealant”, and has no greasebase or component; and (iii) SYNTHACALK (Trademark) GC2+ Two-PartPolysulfide Rubber Sealant, available from Pecora Corporation, locatedat 165 Wambold Road, Harleysville, Pa., which sealant has a publishedelongation property of 500 to 550 percent as measured in accordance withASTM D 412, fully cures in about one day, and has no grease base orcomponent.

Metallic Coating. As also shown in FIGS. 5 and 6, where in analternative embodiment the sealing substance 8, 8′ is a metalliccoating, both at least a portion of the threads of the pin 2 and atleast a portion of the threads of the box 5 are coated with a metalliccoating (see 8, 8′). Preferably, substantially all of the threads ofboth of the pin 2 and the box 5 are coated with either the same ordifferent metallic coating (see 8, 8′); however, the threads may also becoated in a differential way along the threading to provide localizedsealing points. The metallic coating (see 8, 8′) is applied to thethreads of the pin 2 and the box 5 before coupling thereof.

More specifically, where the sealing substance 8, 8′ is a metalliccoating, a first metallic coating (see 8) is disposed on and adhered tothe external male threading 3, and a second metallic coating (see 8′) isdisposed on and adhered to the internal female threading 6. Preferably,each of the first metallic coating (see 8) and the second metalliccoating (see 8′) is a ductile metal with a low yield point, having, forexample, a yielding tension less than about 100 MPa (14.5 k.s.i.). Morepreferably, each of the first metallic coating (see 8) and the secondmetallic coating (see 8′) is a ductile metal and has a yielding tensionless than about 50 MPa (7.25 k.s.i.). Most preferably, each of the firstmetallic coating (see 8) and the second metallic coating (see 8′) is aductile metal and has a yielding tension less than about 20 MPa (2.9k.s.i.). In addition, each of the preferred first metallic coating (see8) and the preferred second metallic coating (see 8′) allows a principalshear strain of at least about 100 percent without fracturing andwithout fissure propagation.

In one aspect of the present invention, each of the first metalliccoating (see 8) and the second metallic coating (see 8′) is a puremetal. “Pure metal”, as that term is used herein, is intended to haveits ordinary meaning as that term is used in the metals art.Nonetheless, in a more preferred embodiment, the pure metal contains99.99 percent by weight of a single metal. This single metal is a metalsuch as, for example, Copper, Aluminum, Lead, Zinc, Tin and Magnesium.More preferably, the single metal is selected from the group consistingof Lead, Zinc and Tin. As initially applied to the threads of the pin 2and the box 5 (i.e., before coupling thereof), each of the firstmetallic coating (see 8) and the second metallic coating (see 8′)preferably has a thickness at least about one-sixteenth of a gap thatexists between the engaged internal female threading 6 and the externalmale threading 3 when the pin 2 and the box 5 are coupled togetherwithout the sealing substance 8, 8′. Most preferably, each of the firstand second metallic coatings (see 8, 8′) has substantially the samethickness and is of the same pure metal. Each of the first and secondmetallic coatings (see 8, 8′) may be applied to the threads of the pin 2and the box 5 by the following conventional methods (though it is notrestricted to them): electrochemical, molten metal bath, hot dipcoating, spray of molten metal, metallic powder, and vapor deposition.

Although the discussion above focused on the use of a pure metal as thesealing substance 8, 8′, one or both of the first and second metalliccoatings (see 8, 8′) may alternatively be alloys. As used herein, analloy is a metal having impurities of up to about five percent (5%) byweight. In other words, an alloy is a metal that contains aboutninety-five percent (95%) or more by weight of a single metal and aboutfive percent (5%) or less by weight of impurities. In this context, thesingle metal is again a metal such as, for example, Copper, Aluminum,Lead, Zinc, Tin and Magnesium. As such, the threads of the pin 2 mayhave a pure metal coating while the threads of the box 5 may have analloy coating.

Furthermore, the most preferred first and second metallic coatings (see8, 8′) are able to recover mechanical properties at about roomtemperature or lower. As used herein, in a material properties context,“room temperature” is understood to be at about 70° F. (21° C.). Theability of these first and second metallic coatings (see 8, 8′) torecover mechanical properties results from their havingrecrystallization temperatures about, preferably below, roomtemperature. For example, the recrystallization temperature of Zinc is50° F. (10° C.), and that of each of Tin and Lead is 25° F. (−3.9° C.).As such, these metals remain strain free, or substantially strain free,during physical manipulation thereof, because each of the metals canreform its structure spontaneously at room temperature. Moreover, duringthe recrystallization stage, metals experience an increase in ductilityand a reduction in tensile strength, which are preferred propertycharacteristics of the most preferred first and second metallic coatings(see 8, 8′). As discussed below, the ability of the first and secondmetallic coatings (see 8, 8′) to recover mechanical properties at aboutroom temperature or lower allows for the first and second metalliccoatings (see 8, 8′) to cold weld to each other without heat treatment.

Most importantly, the first metallic coating (see 8) and the secondmetallic coating (see 8′) of the present invention are selected suchthat when the female threaded element 5 is threadedly engaged with themale threaded element 2 (i.e., made up), the first metallic coating (see8) cold welds to the second metallic coating (see 8′). As used herein,the terms “cold weld” and “cold welding” have their ordinary meaning asused in the metals art. One such meaning of “cold weld” and “coldwelding”, for example, is the forcing together of like or unlike metalsat ambient temperature, often in a shearing manner, so that normal oxidesurface films are ruptured allowing such intimate metal contact thatadhesion takes place. Thus, where the sealing substance 8, 8′ is ametallic coating, the threaded connection is sealed by the cold weldingof the first metallic coating (see 8) with the second metallic coating(see 8′). This cold welding occurs during and as a result of the actionof coupling the coated threads of the pin 2 and the coated threads ofthe box 5. Since the coupling of the pin 2 and the box 5 preferablyoccurs at about room temperature, metallic coatings having the abovedescribed ability to recrystallize at about room temperature promotemore successful cold welding of the metallic coating of the pin 2 withthe metallic coating of the box 5.

Through the use of the first metallic coating (see 8) and the secondmetallic coating (see 8′) of the present invention, a sealed threadedconnection of radially expandable tubulars may be made up, without theneed for other substances, such as thread compounds, between the matingsurfaces of the threads of the tubulars (e.g., the pin 2 and the box 5)to effect the seal. Further to the cold welding discussion above, thecold welding process may also be characterized as a mechanism of plasticdeformation that makes two surfaces (e.g., the first and second metalliccoatings) interpenetrate one another and form a metallic bond betweenthem. In the present invention, this cold welding or “linear frictionwelding” occurs between two surfaces that bear one against the otherwith a normal force that produces galling (i.e., the coated threads ofthe pin 2 bear against the coated threads of the box 5) and supplies themetallic adhesion between the two surfaces (i.e., between the first andsecond metallic coatings (see 8, 8′)). This cold weld additionally actsas a sealing means by forming a single, preferably homogeneous, sealingsubstance 8, 8′ out of the first and second metallic coatings (see 8,8′), wherein that now single sealing substance 8, 8′ remains extendedbetween the external male threading 3 and the internal female threading6 and adhered to both the external male threading 3 and the internalfemale threading 6.

Both the cold welding process and the sealing of the threaded connectionusing an elastomeric sealant are described in more detail below withreference to FIG. 7. FIG. 7 shows a detail of the threads 3, 6 of thepin 2 and the box 5 as the threaded connection is made up. As shown, oneof the external male threads 3 of the pin 2 is in contact with acorresponding internal female thread 6 of the box 5, with the sealingsubstance 8, 8′ already formed (i.e., the sealing substance 8 on the pin2 has become one with the sealing substance 8′ on the box 5) andextended between and adhered to the male and female threading 3, 6. Theflow of the sealing substance 8, 8′ upon engagement of the pin 2 and thebox 5 is shown by means of the arrows 27 along the load flank 26 of theexternal male thread 3 and corresponding flank of the internal femalethread 6. As shown in FIG. 7, the sealing substance 8, 8′ is beingaccumulated in the gap formed between the external male threading 3 andthe internal female threading 6. The radially compressive effect, shownby arrows 28, that the sealing substance 8, 8′ is subjected to duringthe make up or after a radial expansion of the made up threadedconnection is also shown in FIG. 7, which makes visible the mechanism ofcold welding through which sealing of the joint is achieved where thesealing substance 8, 8′ is the first and second metallic coatings. Wherethe sealing substance 8, 8′ is the elastomeric sealant, the radialcompression produces the appropriate allocation of that elastomericsealant in the gap(s), and, if the elastomeric sealant is applied on thethreads of both the pin 2 and the box 5, the radial compression improvesthe mixing of the elastomeric sealant (see 8) on the threads 3 of thepin 2 with the elastomeric sealant (see 8′) on the threads 6 of the box5.

The preferred methods of assembling the sealed, radially expandabletubular assembly 1 of the present invention are further described below.In one aspect, the method of forming a sealed tubular joint 1 of thepresent invention includes providing a first radially expandable tubularmember 2 having external male threading 3 and a first free end 4, theexternal male threading 3 including a first incomplete thread (e.g., 11)and a first hooked thread (e.g., see FIG. 4), the first incompletethread (e.g., 11) being located at least adjacent the first free end 4of the first tubular member 2; and providing a second radiallyexpandable tubular member 5 having internal female threading 6 and asecond free end 7, the internal female threading 6 including a secondincomplete thread (e.g., 12) and a second hooked thread (e.g., see FIG.4), the second incomplete thread (e.g., 12) being located at leastadjacent the second free end 7 of the second tubular member 5.

In a preferred embodiment, the threads 3, 6 of the pin 2 and the box 5are cleaned. The threads 3, 6 may be cleaned using any number ofconventional cleaning methods known, for example, in the oil and gaswell drilling fields. Most preferably, the threads 3, 6 of the pin 2 andthe box 5 are cleaned to substantially remove all foreign material andsurface corrosion. In addition, although not necessary to obtain thesealed, radially expandable tubular assemblies of the present invention,it may be further advantageous to coat the threads 3, 6 of the pin 2and/or the box 5 with primer material, in order, for example, to improvethe adhesion of the sealing substance 8, 8′ to the threads 3, 6 or toprotect the threads 3, 6 once cleaned. This primer material is selectedbased on the particular sealing substance 8, 8′ to be applied to thethreads 3, 6, such that the primer is compatible with that sealingsubstance 8, 8′ and the material composition of the pin 2 and the box 5.

Thereafter, where the sealing substance 8, 8′ is a metallic coating, thepreferred method includes coating the external male threading 3 with afirst metallic coating (see 8), the first metallic coating being a firstpure metal and adhering to the external male threading 3; and coatingthe internal female threading 6 with a second metallic coating, thesecond metallic coating being a second pure metal and adhering to theinternal female threading 6. The selection of the pure metal(s) to usein this coating application is discussed above with respect to thesealed threaded connection itself. After coating the threads 3, 6, thepreferred method includes coupling (i.e., making up) the first tubularmember 2 and the second tubular member 5. This coupling process causesthe first metallic coating to cold weld to the second metallic coatingand vice versa. Furthermore, most preferably, this coupling processincludes applying torque to the threaded connection such that the pinnose 9 seats against (i.e., mates with or engages) the internal torqueshoulder 30 of the box 5. The amounts of torque to be applied andmethods of determining that amount of torque, in order to properly makeup a sealed threaded tubular connection, are well known in the oil andgas well drilling fields. Factors that inform the proper amount oftorque to apply include, by way of non-limiting example, the size of thetubular members, the amount, size, and type of threading on the tubularmembers, the particular sealing substance used, the type of tubularmember material, and the temperature(s) of the tubular members andsealing substance at the time of make up.

Thereafter, the preferred method includes radially expanding thethreaded connection, wherein after this radial expansion of the threadedconnection (i) the first metallic coating (see 8) remains adhered to theexternal male threading 3, (ii) the second metallic coating (see 8′)remains adhered to the internal female threading 6, and (iii) the firstmetallic coating (see 8) and the second metallic coating (see 8′) remaincold welded together to effect a seal. The radial expansion processpreferably radially expands the threaded connection at least about fivepercent based on an inside diameter of the threaded connection, morepreferably at least about fifteen percent based on an inside diameter ofthe threaded connection, and most preferably at least about 25 percentbased on an inside diameter of the threaded connection. As such, aradially expanded threaded tubular assembly or joint 1 is obtained.

In another preferred method of forming a radially expandable threadedtubular joint 1, where the sealing substance 8, 8′ is an elastomericsealant, the preferred method includes coating at least one of (and mostpreferably both of) the external male threading 3 and the internalfemale threading 6 with an elastomeric sealant (see 8, 8′). Theselection of the elastomeric sealant(s) (see 8, 8′) to use in thiscoating application is discussed above with respect to the sealedthreaded connection itself. This elastomeric sealant(s) (see 8, 8′) maybe applied to the threads using conventional sealant applicationprocesses, which are well known in the oil and gas well drilling fields.The preferred elastomeric sealant(s) (see 8, 8′), as discussed above,adhere to the threads 3, 6 of the pin 2 and the box 5. After coating thethreads 3, 6, the preferred method includes coupling (i.e., making up)the first tubular member 2 and the second tubular member 5 before theelastomeric sealant (see 8, 8′) has fully cured. This coupling actiondisposes the elastomeric sealant (see 8, 8′) between the external malethreading 3 and the internal female threading 6 (see, e.g., FIG. 7), andmore particularly, within the gaps between the threads of the coupledthreaded connection.

Thereafter, the preferred method includes curing the elastomeric sealant(see 8, 8′). The curing process provides a cured elastomeric sealantextended between and adhered to the external male threading 3 and theinternal female threading 6. After curing, the preferred method includesradially expanding the threaded connection, wherein after this radialexpansion of the threaded connection the elastomeric sealant (see 8, 8′)remains extended between and adhered to the external male threading 3and the internal female threading 6. The radial expansion processpreferably radially expands the threaded connection at least about fivepercent based on an inside diameter of the threaded connection, morepreferably at least about fifteen percent based on an inside diameter ofthe threaded connection, and most preferably at least about 25 percentbased on an inside diameter of the threaded connection. As such, aradially expanded threaded tubular assembly or joint 1 is obtained.

FIG. 10 generally shows schematically an expansion process as it istaking place along a plain end pipe 33, which is a pipe without threads.In FIG. 10, a mandrel 34 for use in radially expanding the plain endpipe 33 is moving out of the plain end pipe 33 (to the left in thedrawing). FIG. 11 illustrates a “spring-back” movement at the free end35 of the plain end pipe 33 as the mandrel 34 is removed from withinthat pipe 33. As a result of the spring-back movement, the free end 35of the plain end pipe 33 has a smaller inner diameter than the innerdiameter of a portion of the pipe 33 further up from that free end 35.

FIG. 12 shows a made up threaded tubular connection being radiallyexpanded, which is taking place in a direction from the pin 2 to the box5. As shown in FIG. 12, the mandrel 34 is pushed along the threadedtubular connection to produce such a radial deformation. FIG. 13 showsthe threaded tubular connection of FIG. 12 after that threaded tubularconnection has been expanded by the mandrel 34. As shown, the mandrel 34has already passed the threads 3, 6 of the pin 2 and the box 5, and hasstarted expanding the remaining length of the female threaded element 5.FIG. 14 illustrates in more detail an area of the threaded connectiononce the mandrel 34 has passed beyond the threads of that threadedconnection, and particularly shows the pin nose 9 located at the firstfree end 4 of the pin 2 after radial expansion and the reverse torqueshoulder 30. As further illustrated by FIG. 14, it is shown that becauseof the reverse torque shoulder 30, the pin nose 9 has not suffereddeformation towards the inside of the tubular member, i.e., the pin nose9 has not suffered the “spring-back” effect explained above withreference to FIGS. 10 and 11.

While this invention has been described with reference to what arecurrently considered to be the preferred embodiments, it is to beunderstood that the invention is not limited to the disclosedembodiments. On the contrary, the invention is intended to cover variousmodifications and equivalent arrangements included within the spirit andscope of the appended claims. The scope of the following claims is to beaccorded the broadest interpretation so as to encompass all suchmodifications and equivalent structures and functions.

1. A radially expandable threaded tubular assembly comprising: aradially expandable male threaded element having external male threadingand a first free end, the external male threading including a firstincomplete thread and a first hooked thread, the first incomplete threadbeing located at least adjacent the first free end of said male threadedelement; a radially expandable female threaded element having internalfemale threading and a second free end, the internal female threadingincluding a second incomplete thread and a second hooked thread, thesecond incomplete thread being located at least adjacent the second freeend of said female threaded element, said female threaded element beingthreadedly engaged with said male threaded element; and an elastomericsealant extending between the external male threading and the internalfemale threading and adhering to both the external male threading andthe internal female threading, said elastomeric sealant capable of beingelongated after curing while remaining extended between and adhered tothe external male threading and the internal female threading.
 2. Anassembly according to claim 1, wherein said elastomeric sealant iscapable of being elongated at least about 45 percent after curing whileremaining extended between and adhered to each of the external malethreading and the internal female threading and has an elastic modulusless than about 2.0 MPa (290 p.s.i.).
 3. An assembly according to claim1, wherein said elastomeric sealant is capable of being elongated atleast about 100 percent after curing while remaining extended betweenand adhered to each of the external male threading and the internalfemale threading and has an elastic modulus less than about 1.0 MPa (145p.s.i.).
 4. An assembly according to claim 1, wherein said elastomericsealant is capable of being elongated at least about 400 percent aftercuring while remaining extended between and adhered to each of theexternal male threading and the internal female threading and has anelastic modulus between about 0.5 MPa (73 p.s.i.) and about 2.0 MPa (290p.s.i.).
 5. An assembly according to claim 4, wherein said elastomericsealant is adhered to each of the external male threading and theinternal female threading with an adhesion-to-rigid-substrate of atleast 0.35 MPa (51 p.s.i.).
 6. An assembly according to claim 4, whereinsaid elastomeric sealant is adhered to each of the external malethreading and the internal female threading with anadhesion-to-rigid-substrate of at least 0.7 MPa (102 p.s.i.).
 7. Anassembly according to claim 6, wherein said elastomeric sealant is agreaseless elastomeric sealant.
 8. An assembly according to claim 7,wherein said greaseless elastomeric sealant is capable of curing in theabsence of oxygen and in the absence of humidity.
 9. An assemblyaccording to claim 8, wherein said greaseless elastomeric sealant is apolysulfide sealant or a polyurethane sealant.
 10. An assembly accordingto claim 9, wherein said greaseless elastomeric sealant is a viscouspaste or a liquid before curing and is a rubber-like solid after curing.11. An assembly according to claim 1, wherein said male threaded elementand said female threaded element threadedly engage each other to form aflush joint connection.
 12. An assembly according to claim 11, whereineach of the first incomplete thread and the second incomplete thread hasa perfect crest and an imperfect root.
 13. An assembly according toclaim 12, wherein each of the first incomplete thread and the secondincomplete thread is also a hooked thread.
 14. An assembly according toclaim 13, wherein the first incomplete thread is the initial threadadjacent the first free end of said male threaded element, and thesecond incomplete thread is the initial thread adjacent the second freeend of said female threaded element.
 15. An assembly according to claim14, wherein at least one of said male threaded element and said femalethreaded element includes a torque shoulder.
 16. An assembly accordingto claim 15, wherein the torque shoulder is a reverse torque shoulder.17. A radially expandable threaded tubular assembly comprising: aradially expandable male threaded element having external male threadingand a first free end, the external male threading including a firstincomplete thread and a first hooked thread, the first incomplete threadbeing located at least adjacent the first free end of said male threadedelement; a radially expandable female threaded element having internalfemale threading and a second free end, the internal female threadingincluding a second incomplete thread and a second hooked thread, thesecond incomplete thread being located at least adjacent the second freeend of said female threaded element; a first metallic coating disposedon and adhered to the external male threading; and a second metalliccoating disposed on and adhered to the internal female threading,wherein said female threaded element is threadedly engaged with saidmale threaded element and said first metallic coating is cold welded tosaid second metallic coating.
 18. An assembly according to claim 17,wherein each of said first metallic coating and said second metalliccoating is a ductile metal and has a yielding tension less than about100 MPa (14.5 k.s.i.).
 19. An assembly according to claim 17, whereineach of said first metallic coating and said second metallic coating isa ductile metal and has a yielding tension less than about 20 MPa (2.9k.s.i.).
 20. An assembly according to claim 19, wherein each of saidfirst metallic coating and said second metallic coating allows aprincipal shear strain of at least about 100 percent without fracturingand without fissure propagation.
 21. An assembly according to claim 17,wherein one of said first metallic coating and said second metalliccoating is an alloy, and the other of said first metallic coating andsaid second metallic coating is an alloy or a pure metal.
 22. Anassembly according to claim 17, wherein each of said first metalliccoating and said second metallic coating is a pure metal.
 23. Anassembly according to claim 22, wherein the pure metal contains 99.99percent by weight of a single metal.
 24. An assembly according to claim23, wherein the single metal is selected from the group consisting ofCopper, Aluminum, Lead, Zinc, Tin and Magnesium.
 25. An assemblyaccording to claim 23, wherein the single metal is selected from thegroup consisting of Lead, Zinc and Tin.
 26. An assembly according toclaim 25, wherein each of said first metallic coating and said secondmetallic coating has a thickness at least about one-sixteenth of a gapbetween the engaged internal female threading and the external malethreading.
 27. An assembly according to claim 26, wherein each of saidfirst metallic coating and said second metallic coating hassubstantially the same thickness and is of the same pure metal.
 28. Anassembly according to claim 26, wherein at least one of said firstmetallic coating and said second metallic coating has a varyingthickness, and each of said first metallic coating and said secondmetallic coating is of the same pure metal.
 29. An assembly according toclaim 17, wherein said radially expandable male threaded element andsaid radially expandable female threaded element threadedly engage eachother to form a flush joint connection.
 30. An assembly according toclaim 29, wherein each of the first incomplete thread and the secondincomplete thread has a perfect crest and an imperfect root.
 31. Anassembly according to claim 30, wherein each of the first incompletethread and the second incomplete thread is also a hooked thread.
 32. Anassembly according to claim 31, wherein the first incomplete thread isthe initial thread adjacent the first free end of said male threadedelement, and the second incomplete thread is the initial thread adjacentthe second free end of said female threaded element.
 33. An assemblyaccording to claim 32, wherein at least one of said male threadedelement and said female threaded element includes a torque shoulder. 34.An assembly according to claim 33, wherein the torque shoulder is areverse torque shoulder.
 35. A method of forming a sealed tubular joint,said method comprising the steps of: providing a first radiallyexpandable tubular member having external male threading and a firstfree end, the external male threading including a first incompletethread and a first hooked thread, the first incomplete thread beinglocated at least adjacent the first free end of the first tubularmember; providing a second radially expandable tubular member havinginternal female threading and a second free end, the internal femalethreading including a second incomplete thread and a second hookedthread, the second incomplete thread being located at least adjacent thesecond free end of the second tubular member; coating at least one ofthe external male threading and the internal female threading with anelastomeric sealant; coupling the first tubular member and the secondtubular member, said coupling thereby providing a threaded connection;disposing the elastomeric sealant between the external male threadingand the internal female threading and into adherence with each of theexternal male threading and the internal female threading; curing theelastomeric sealant, said curing thereby providing a cured elastomericsealant extended between and adhered to the external male threading andthe internal female threading; and radially expanding the threadedconnection, wherein the cured elastomeric sealant is capable of beingelongated while remaining extended between and adhered to the externalmale threading and the internal female threading.
 36. A method accordingto claim 35, wherein the threaded connection is radially expanded atleast about five percent based on an inside diameter of the threadedconnection.
 37. A method according to claim 35, wherein the threadedconnection is radially expanded at least about fifteen percent based onan inside diameter of the threaded connection.
 38. A method according toclaim 35, wherein the elastomeric sealant is a greaseless elastomericsealant, each of the external male threading and the internal femalethreading is coated with the greaseless elastomeric sealant in saidcoating step, and the cured elastomeric sealant (i) is capable of beingelongated at least about 400 percent while remaining extended betweenand adhered to the external male threading and the internal femalethreading, (ii) is adhered to each of the external male threading andthe internal female threading with an adhesion-to-rigid-substrate of atleast 0.7 MPa (102 p.s.i.); and (iii) has an elastic modulus betweenabout 0.5 MPa (73 p.s.i.) and about 2.0 MPa (290 p.s.i.).
 39. A methodaccording to claim 38, wherein the greaseless elastomeric sealant is (i)a polysulfide sealant or a polyurethane sealant, (ii) a viscous paste ora liquid before said curing, and (iii) a rubber-like solid after saidcuring.
 40. A method according to claim 35, wherein (i) the threadedconnection is a flush joint connection, (ii) each of the firstincomplete thread and the second incomplete thread has a perfect crestand an imperfect root, (iii) each of the first incomplete thread and thesecond incomplete thread is also a hooked thread, (iv) the firstincomplete thread is the initial thread adjacent the first free end ofthe first tubular member and the second incomplete thread is the initialthread adjacent the second free end of the second tubular member, and(v) at least one of the first tubular member and the second tubularmember includes a reverse torque shoulder.
 41. A method of forming asealed tubular joint, said method comprising the steps of: providing afirst radially expandable tubular member having external male threadingand a first free end, the external male threading including a firstincomplete thread and a first hooked thread, the first incomplete threadbeing located at least adjacent the first free end of the first tubularmember; providing a second radially expandable tubular member havinginternal female threading and a second free end, the internal femalethreading including a second incomplete thread and a second hookedthread, the second incomplete thread being located at least adjacent thesecond free end of the second tubular member; coating the external malethreading with a first metallic coating, the first metallic coatingbeing a first pure metal and adhering to the external male threading;coating the internal female threading with a second metallic coating,the second metallic coating being a second pure metal and adhering tothe internal female threading; coupling the first tubular member and thesecond tubular member, said coupling thereby providing a threadedconnection, said coupling cold welding the first metallic coatingtogether with the second metallic coating; and radially expanding thethreaded connection, wherein after said radial expansion of the threadedconnection (i) the first metallic coating remains adhered to theexternal male threading, (ii) the second metallic coating remainsadhered to the internal female threading, and (iii) the first metalliccoating and the second metallic coating remain cold welded together. 42.A method according to claim 41, wherein the threaded connection isradially expanded at least about five percent based on an insidediameter of the threaded connection.
 43. A method according to claim 41,wherein the threaded connection is radially expanded at least aboutfifteen percent based on an inside diameter of the threaded connection.44. A method according to claim 41, wherein (i) each of the first puremetal and the second pure metal contains 99.99 percent by weight of asingle metal selected from the group consisting of Copper, Aluminum,Lead, Zinc, Tin and Magnesium, (ii) the threaded connection is a flushjoint connection, (iii) each of the first incomplete thread and thesecond incomplete thread has a perfect crest and an imperfect root, (iv)each of the first incomplete thread and the second incomplete thread isalso a hooked thread, and (v) at least one of the first tubular memberand the second tubular member includes a reverse torque shoulder.
 45. Anexpandable sealed tubular joint comprising: a pair of radiallyexpandable elements each having threading at a free end thereof andcoupled to one another, the threading including hooked incompletethreads being located at least adjacent the free ends; and a sealingsubstance extending between and adhering to the threading of oneradially expandable element and the threading of the other radiallyexpandable element, wherein after a radial expansion of said coupledpair of radially expandable elements said sealing substance remainsextended between and adhered to the threading of one radially expandableelement and the threading of the other radially expandable element. 46.A joint according to claim 45, wherein said sealing substance is agreaseless elastomeric sealant that (i) is capable of being elongated atleast about 100 percent while remaining extended between and adhered tothe threading of one radially expandable element and the threading ofthe other radially expandable element, (ii) is adhered to the threadingwith an adhesion-to-rigid-substrate of at least 0.35 MPa (51 p.s.i.);and (iii) has an elastic modulus between about 0.5 MPa (73 p.s.i.) andabout 2.0 MPa (290 p.s.i.).
 47. A joint according to claim 45, whereinsaid sealing substance is a pure metal containing 99.99 percent byweight of a single metal selected from the group consisting of Copper,Aluminum, Lead, Zinc, Tin and Magnesium, said coupled pair of radiallyexpandable elements form a flush joint connection, and the hookedincomplete threads have perfect crests and imperfect roots.